RC-IGBTs (reverse-conducting insulated gate bipolar transistor) monolithically integrate an IGBT and a free-wheeling diode. When the RC-IGBT is forward biased, the RC-IGBT is effective as an electronic switch capable of switching on and off a current flowing in a first direction between a collector and an emitter terminal, wherein the current is subject to a gate potential applied to a gate terminal and capacitively controlling a transistor channel. The RC-IGBT is in a transistor mode as long as a unipolar electron current through the transistor channel is below a threshold beyond which a voltage drop across the pn junction along p-type anode zones is sufficiently high such that the anode zones start injecting holes into the drift layer and a bipolar current flows in an IGBT mode. When the RC-IGBT is reverse biased, the RC-IGBT operates in a diode or reverse conducting mode and conducts a current flowing opposite to the first direction irrespective of the gate potential.
Typically, improving the characteristics of one mode of multi-mode semiconductor devices such as RC-IGBTs adversely affects another mode. It is desirable to improve the device characteristics of multi-mode semiconductor devices with less adverse impact on other device characteristics.